Apparatus for electrically upsetting pipe ends



July 27, 1943. w. E. CRAWFORD 2,325,480

APPARATUS FOR ELECTRICALLY UPSETTING PIPE ENDS Filed Nov. 19, 1942 WilliamECmwford INVENTOR.

AT T01? HEY- Patented July 27, 1943 APPARATUS FOR ELECTRICALLY UPSETTING PIPE nuns William E. Crawford, Wauwatosa,

to A. 0. Smith Corporation,

Wis'., asslgnor Milwaukee, Wis., a

corporation 01' New York Application November 19, 1942, Serial No. 466,135

I 6 Claims. (Cl. 2193) This invention relates to apparatus for electrically upsetting tube ends and constitutes an improvement in the apparatus set forth and described in the co-pending application of Axel Westin and Sven Westin, Serial No. 466,170, filed Nov. 19, 1942, for Method and apparatus for upsetting pipe ends.

In the apparatus described in the application referred to, the pipe end is fed into a circular die cavity or groove in the face of a plurality of circumferentially spaced segmental electrodes, the die cavity being formed between an outer shell and central plug with the side walls of the cavity tapered and with the mouth of the cavity serving to straighten the upset end as it is withdrawn from the die.

An object of the present invention is to facilitate withdrawal of the upset end of the blank from the die.

Another object of the invention is to reduce the friction between the substantially inactive die surfaces and the blank during upsetting of the latter.

Other objects and advantages will appear hereinafter in the description of embodiments of the invention illustrated in the accompanying drawing.

In the drawing:

Figure 1 is a diagrammatic longitudinal axial section through apparatus embodying the invention showing the blank about to be upset;

Fig. 2 is a fragmentary view of a section similar to Fig. 1 showing the blank partially upset;

Fig. 3 is a similar view showing completion of the upsetting operation;

Fig. 4 is a similar section through the upset blank after withdrawal from the die;

Fig. 5 is a view similar to Fig. 1 showing a modified construction of apparatus embodying the invention; and

Fig. 6 is a fragmentary longitudinal sectional view of the completed upset blank after removal from the die shown in Fig. 5.

In carrying out the invention, the taper of the surface of the die cavity engaged by the incoming blankis' reduced to a minimum and is provided just sufficient to give adequate electrical contact between the electrode dies and the blank for heating the latter. The opposite surface of the die cavity is allowed to rotate with the incoming blank to reduce the friction of the die against the heated section of the blank. This is accomplished by separating the die into an outer member and an inner member disposed to provide outer and inner concentric die surfaces and to rotate relative to one another. One of the members, preferably the stationary member, is split longitudinally to provide segmental insu lated electrodes for conducting heating current to the blank. The die cavity provided between the members is in the form of a circular groove of gradually decreasing width from its mouth to its bottom, the bottom of the groove being closed by a flange on one of the members.

Referring to the drawing, the apparatus illustrated in Figs. 1 to 3 comprises a rotary chuck l for gripping a pipe 2 at one-end and moving it axially toward and into the die 3 disposed at the other end of the pipe. I

The die 3 comprises an outer stationary shell 4 and an inner freely rotating plug 5. The shell 4 is generally cylindrical and is made up of a plurality of segmental circumferentially spaced enectrode die members connected to the opposite terminals of a source of heating current by leads 6. The electrodes are held in position by a fixed plate 1 at the rear and are insulated therefrom by insulation 8 extending in a transverse plane. The inner surface of the shell 4, comprising the electrodes, plate and insulation, is tapered to a smaller diameter toward the plate I from the other end of the electrodes which constitutes the mouth of the die. This inner surface of the shell 4 constitutes the outer surface of the die cavity 9, and has a diameter at the mouth of the die slightly larger than the outside, diameter of the blank'2 to be upset.

As the blank 2 is rotated and fed into the die,

the end of the blank engages the inner surface of the electrodes... and heating current passes through the blank in the areas between the elec trodes. As the blank becomes heated, it softens and any tendency for it to lose its contact pressure with the electrodes is prevented by continued feeding of the blank into the 'die cavity, resulting in a slight reduction in the diameter of the blank end.

The plug 5 constitutes a central member having an outer surface It constituting the inner surface of the die cavity 9, and a rear flange ll constituting an abutment for receiving the end of the blank. The plug 5 is mounted on a stub shaft l2 supported in a suitable bearing l3 for free rotation. The rear flange H of the plug presses against the plate I of the outer shell and closes the groove of the die cavity. I v

In operation, as the end of the blank 2 reaches the abutment flange I I, it has passed the electrodes of the shell 4 and is no longer being heated. Its residual heat, however, results in an upsetting of the end against the abutment as the blank continues to move into the die cavity. The plug 5, being engaged by the end of the blank and by the upset metal thereof filling the bottom of the die cavity and contacting the outer surface of the plug, rotates freely with the blank 2. As the blank is fed into the die cavity 9, the latter is gradually filled with the upset metal beginning at the bottom of the cavity and progressively extending toward the mouth of the cavity.

The outer surface I of the plug is preferably tapered to a larger diameter toward the flange H so that the die cavity 9 has its greatest radial width at its mouth and is narrowest at the abutment, the diameter of the plug at the mouth of the cavity being substantially less than the inside diameter of the blank to provide for up setting of the blank end.

After upsetting of the pipe end, the latter can readily be withdrawn from the die cavity by a straight axial movement. The finished pipe as shown in Fig. 4 has its body M of cylindrical shape and its end I5 upset inwardly as shown. The end I5 is tapered on bothsurfaces.

The pipe end may be upset outwardly instead of inwardly. For this purpose, the apparatus shown in Fig. 5 is employed. In the apparatus of Fig. 5 the central plug I6 is held stationary and is longitudinally split into segmental electrodes for supplying current to the blank, While the outer shell I1 is mounted in a bearing support l8 for free rotation with the blank.

The flange IS on the plug is electrically insulated from the electrodes and constitutes the end abutment closing the bottom of the die cavity 20.

The inner surface of the cavity 20, formed by the electrodes, is tapered to a larger diameter at the inner end of the cavity, the outer end of the surface having a diameter slightly less than the inside diameter of the blank for receiving the blank and passing current thereto. The outer surface of the cavity, formed by the cylindrical shell I1, is substantially larger in diameter than the outer diameter of the blank and is tapered to a smaller diameter toward the inner end of the cavity.

The principle of operation of the apparatus shown in Fig. 5 is substantially the same as that of the apparatus shown in Figs. 1 to 3. However, the heating current is supplied to the blank by the internal electrodes of plug l6 instead of being supplied by the external electrodes of shell 4, and the upsetting of the blank is radially outward from the e1-atrodes of plug I6 instead of being radially inward from the electrodes of shell 4,

Various embodiments of the invention may be employed within the scope of the accompanying claims.

The invention is claimed as follows:

1. The improvement in apparatus of the class described, comprising an upsetting die with a circular cavity closed at its bottom for upsetting the end of a rotating tubular blank, the outer shell of the die and the central plug thereof being mounted for relative rotation with one member fixed and the other member free to rotate with the blank, and one of said members comprising circumferentially spaced electrode die segments lfilirmiupplying electric heating current to the 2. The improvement in apparatus of the class described, comprising an upsetting die with a circular cavity closed at its bottom for upsetting the end of a rotating tubular blank, the outer shell of the die and the central plug thereof being mounted for relative rotation with one member fixed and the other member free to rotate with the blank, one of said members comprising circumferentially spaced electrode die segments for supplying electric heating current to the blank, said electrodes having a tapered forming surface engaged by the blank as the latter is fed into the die cavity, and the forming surface opposed to the electrodes being tapered in the opposite direction and radially spaced from the electrodes to receive and shape the upset metal.

3. The improvement in apparatus of the class described, comprising an upsetting die with a circular cavity closed at its bottom for upsetting the end of a rotating tubular blank, the outer shell of the die and the central plug thereof being mounted for relative rotation with one member free to rotate with the blank and the other member comprising circumferentially spaced electrode die segments for supplying electric heating current to the blank as the latter rotates in contact therewith.

4. The improvement in apparatus of the class described, comprising an upsetting die with a circular cavity closed at its bottom for upsetting the end of a rotating tubular blank, the outer shell of the die and the central plug thereof being mounted for relative rotation with one member free to rotate with the blank and the other member comprising circumferentially spaced electrode die segments for supplying electric heating current to the blank, said electrodes having a tapered forming surface engaged by the blank as the latter is fed into the die cavity, and the forming surface of the freely rotatable member opposing the electrodes being tapered in the opposite direction and radially spaced from the electrodes to receive and shape the upset metal.

5. In an apparatus of the class described for upsetting the end of a tubular blank, an outer shell comprising circumferentially spaced electrode die segments connected to a source of heating current and having an inner tapered forming surface to be engaged by the outer surface of a rotating blank to be upset, 'a central plug mounted for free rotation and having an outer surface tapered in a direction opposite to that of said inner tapered surface'of the electrodes and providing a circular tapered die cavity having its greatest radial width at its mouth, and an a-butment for closing the rear end of said die cavity.

6. In an apparatus of the class described for upsetting the end of a tubular blank, an inner plug comprising circumferentially spaced electrode die segments connected to a source of heating current and having an outer tapered forming surface to be engaged by the inner surface of a rotating blank to be upset, an outer shell mounted for free rotation and having an inner surface tapered in a direction opposite to said outer tapered surface of the electrodes and providing a circular tapered die cavity having its greatest radial width at its mouth, and an abutment for closing the rear end of said die cavity.

WILLIAM E. CRAWFORD. 

